At least one fairly complete draft for allowing concrete types to be declared inside protocols was at some point a PR in the swift-evolution repo. Worth taking a look at.<br><br>The chief source of complexity is in terms of how to refer to or capture types or members of the containing type or protocol. In the draft I remember, protocols could be nested inside types, and types could be nested inside protocols. Whether and how a protocol with associated type requirements inside a generic type inside another protocol with associated type requirements can refer to types or members of the outermost protocol gets quickly very convoluted; this requires careful design.<br><br><div class="gmail_quote"><div dir="ltr">On Sat, Jul 8, 2017 at 20:59 Jonathan Hull via swift-evolution <<a href="mailto:swift-evolution@swift.org">swift-evolution@swift.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="word-wrap:break-word">The idea (at least for me) is to namespace the enum within the protocol, so that users of the protocol have everything neatly packaged. Right now I have to make a Separate “FoozleErrors” enum, which just feels messy.<div><br></div><div>I would really like to see us be able to nest Structs, Enums, and even other Protocols within a protocol, and it would just act as a namespace. Wil is right though, that if we can only have one, Enums give us the most bang for our buck. That is the case I run into most often. In addition to Error Enums, I also have a lot of places where protocol functions return a classification (as an enum), and it is cluttering the top-level namespace with things named “Foozle____".</div><div><br></div><div>It isn’t a huge issue (it doesn’t stop me from doing anything), but it is an annoyance that I run into all the time… I view the fact that Swift doesn’t support this as a bug.</div><div><br></div><div>Thanks,</div><div>Jon<br><div><div><div><br></div><div><br><div><blockquote type="cite"><div>On Jul 8, 2017, at 6:10 PM, Akshay Hegde <<a href="mailto:akshay_hegde@me.com" target="_blank">akshay_hegde@me.com</a>> wrote:</div><br class="m_-9067813258815646445Apple-interchange-newline"><div><div style="word-wrap:break-word;line-break:after-white-space">Wouldn’t the following work just as well for providing a namespace?<div><br></div><div><span style="font-family:SFMono-Regular;font-size:12px">struct Foozle {</span></div></div></div></blockquote></div></div></div></div></div></div><div style="word-wrap:break-word"><div><div><div><div><div><blockquote type="cite"><div><div style="word-wrap:break-word;line-break:after-white-space"><div><br style="font-family:SFMono-Regular;font-size:12px"> <span style="font-family:SFMono-Regular;font-size:12px">enum Errors: Error {</span><br style="font-family:SFMono-Regular;font-size:12px"> <span style="font-family:SFMono-Regular;font-size:12px">case malformedFoozle</span><br style="font-family:SFMono-Regular;font-size:12px"> <span style="font-family:SFMono-Regular;font-size:12px">case tooManyFoozles</span><br style="font-family:SFMono-Regular;font-size:12px"> <span style="font-family:SFMono-Regular;font-size:12px">}</span><br style="font-family:SFMono-Regular;font-size:12px"><font face="SFMono-Regular"><span style="font-size:12px">}</span></font></div></div></div></blockquote></div></div></div></div></div></div><div style="word-wrap:break-word"><div><div><div><div><div><blockquote type="cite"><div><div style="word-wrap:break-word;line-break:after-white-space"><div></div><div><div></div></div><div>
<div dir="auto" style="letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;word-wrap:break-word"><br>~Akshay</div>
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<div><br><blockquote type="cite"><div>On Jul 8, 2017, at 17:24, Jonathan Hull via swift-evolution <<a href="mailto:swift-evolution@swift.org" target="_blank">swift-evolution@swift.org</a>> wrote:</div><br class="m_-9067813258815646445Apple-interchange-newline"><div><div>I *really* want this as well.<br><br>I think there was a serious proposal to do this early in Swift 4. Not sure why it stalled, but I seem to remember it being technically possible.<br><br>Thanks,<br>Jon<br><br><blockquote type="cite">On Jul 8, 2017, at 4:21 PM, William Shipley via swift-evolution <<a href="mailto:swift-evolution@swift.org" target="_blank">swift-evolution@swift.org</a>> wrote:<br><br>Does anyone know if there's some good tech reason to not allow, like:<br><br>protocol Foozle {<br><span class="m_-9067813258815646445Apple-tab-span" style="white-space:pre-wrap"> </span>enum Errors: Error {<br><span class="m_-9067813258815646445Apple-tab-span" style="white-space:pre-wrap"> </span><span class="m_-9067813258815646445Apple-tab-span" style="white-space:pre-wrap"> </span>case malformedFoozle<br><span class="m_-9067813258815646445Apple-tab-span" style="white-space:pre-wrap"> </span><span class="m_-9067813258815646445Apple-tab-span" style="white-space:pre-wrap"> </span>case tooManyFoozles<br><span class="m_-9067813258815646445Apple-tab-span" style="white-space:pre-wrap"> </span>}<br>}<br><br>Like, to me all this is doing is giving “Errors” a nice namespace, but the compiler might have other thoughts.<br><br>-W<br>_______________________________________________<br>swift-evolution mailing list<br><a href="mailto:swift-evolution@swift.org" target="_blank">swift-evolution@swift.org</a><br><a href="https://lists.swift.org/mailman/listinfo/swift-evolution" target="_blank">https://lists.swift.org/mailman/listinfo/swift-evolution</a><br></blockquote><br>_______________________________________________<br>swift-evolution mailing list<br><a href="mailto:swift-evolution@swift.org" target="_blank">swift-evolution@swift.org</a><br><a href="https://lists.swift.org/mailman/listinfo/swift-evolution" target="_blank">https://lists.swift.org/mailman/listinfo/swift-evolution</a><br></div></div></blockquote></div><br></div></div></blockquote></div></div></div></div></div></div>_______________________________________________<br>
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